Wholly aromatic polyester resins long have been known. For instance, 4-hydroxybenzoic acid homopolymer and co-polymers have been provided in the past and are commercially available. Those wholly aromatic polyesters normally encountered in the prior art have tended to be somewhat intractable in nature and to present substantial difficulties if one attempts to melt process the same while employing conventional melt processing procedures. Such polymers commonly are crystalline in nature, relatively high melting or possess a decomposition temperature which is below the melting point. Other amorphous wholly aromatic polyesters when molten frequently exhibit an isotropic melt phase. With the crystalline polymers molding techniques such as compression molding or sintering may be utilized; however, injection molding, melt spinning, etc., commonly have not been viable alternatives or when attempted commonly have been accomplished with difficulty.
Representative publications which discuss wholly aromatic polyesters include: (a) Polyesters of Hydroxybenzoic Acids, by Russell Gilkey and John R. Caldwell, J. of Applied Polymer Sci., Vol. II, Pages 198 to 202 (1959), (b) Polyarylates (Polyesters from Aromatic Dicarboxylic Acids and Bisphenols), by G. Bier, Polymer, Vol. 15, Pages 527 to 535 (August 1974), (c) Aromatic Polyester Plastics, by S. G. Cottis, Modern Plastics, Pages 62 to 63 (July 1975); and (d) Poly(p-Oxybenzoyl Systems): Homopolymer for Coatings: Copolymers for Compression and Injection Molding, by Roger S. Storm and Steven G. Cottis, Coating Plast. Preprint, Vol. 34, No. 1, Pages 194 to 197 (April, 1974). See also, U.S. Pat. Nos. 3,039,994; 3,169,121; 3,321,437; 3,549,593; 3,553,167; 3,637,595; 3,651,014; 3,723,388; 3,759,870; 3,767,621; 3,778,410; 3,787,370; 3,790;528; 3,829,406; 3,890,256; and 3,975,487.
Also, it more recently has been disclosed that certain polyesters may be formed which exhibit melt anisotropy. See, for instance, (a) Polyester X7G-A Self Reinforced Thermoplastic, by W. J. Jackson Jr., H. F. Kuhfuss, and T. F. Gray, Jr., 30th Anniversary Technical Conference, 1975 Reinforced Plastics/Composites Institute, The Society of the Plastics Industry, Inc., Section 17-D, Pages 1 to 4, (b) Belgian Pat. Nos. 838,935 and 828,936, (c) Dutch Pat. No. 7505551, (d) West German Nos. 2520819, 2520820, 2722120, 2834535, 2834536 and 2834537, (e) Japanese Nos. 43-223; 2132-116; 3017-692; and 3021-293, (f) U.S. Pat. Nos. 3,991,013; 3,991,014; 4,057,597; 4,066,620; 4,067,852; 4,075,262; 4,083,829; 4,118,372; 4,130,545; 4,130,702; 4,153,779; 4,156,070; 4,159,365; 4,161,470; 4,169,933; 4,181,792; 4,183,895; 4,184,996; and 4,188,476; (g) U.K. Application No. 2,002,404; and (h) European Patent Application No. 0008855. See also commonly assigned U.S. Ser. Nos. 10,392, and 10,393, filed Feb. 8, 1979 and now U.S. Pat. No. 4,238,599 and 4,238,598, issued Dec. 9, 1980; 17,007, filed Mar. 2, 1979 now U.S. Pat. No. 4,230,819 issued Oct. 28, 1980; 21,050, filed Mar. 16, 1979 now U.S. Pat. No. 4,224,433 issued Sept. 23, 1980; 32,086, filed Apr. 23, 1979 now U.S. Pat. No. 4,219,461 issued Aug. 26, 1980; 54,049, filed July 2, 1979 now U.S. Pat. No. 4,256,624 issued Mar. 17, 1981; 91,003, filed Nov. 5, 1979; 109,573, filed Jan. 4, 1980 now U.S. Pat. No. 4,265,802 issued May 5, 1981; 109,574, filed Jan. 4, 1980; 128,759, filed Mar. 10, 1980; and 128,778, filed Mar. 10, 1980 now U.S. Pat. No. 4,279,803 issued July 21, 1981.
In commonly assigned U.S. Pat. No. 4,219,461, is claimed a melt processable wholly aromatic polyester consisting essentially of 6-oxy-2-naphthoyl moieties, p-oxybenzoyl moieties, symmetrical dioxyaryl moieties, and symmetrical dicarboxyaryl moieties in the proportions there indicated. See also commonly assigned U.S. Pat. No. 4,161,470 which claims a melt processable wholly aromatic polyester consisting essentially of 6-oxy-2-naphthoyl moieties and p-oxybenzoyl moieties in the proportions indicated, and U.S. Pat. No. 4,156,070 to Jackson et al and the disclosures discussed therein.
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester which is capable of forming quality molded articles, fibers, etc. which exhibit substantially more flexibility than if formed from the polyester of U.S. Pat. No. 4,219,461, without any significant sacrifice of other highly desirable properties.
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester which is capable of forming molded articles of unusually high impact strength, toughness, and extensibility, in combination with other highly desirable mechanical properties.
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester capable of formng an anisotropic melt phase at a temperature below approximately 350.degree. C., and preferably below approximately 325.degree. C.
It is an object of the present invention to provide an improved wholly aromatic polyester which forms a highly tractable melt phase which exhibits improved moldability.
These and other objects, as well as the scope, nature and utilization of the invention will be apparent to those skilled in the art from the following detailed description.